[2] He was one of the founding members of the short-lived proto-punk band Rocket from the Tombs (1974–1975), in which he played under the moniker "Crocus Behemoth," and of post-punk group Pere Ubu (1975–present, intermittently).

Afterwards, Thomas worked with a variety of musicians including guitarists Richard Thompson and Philip Moxham, and Henry Cow alumni bassonist/oboist Lindsay Cooper and drummer Chris Cutler.

Throughout the 1980s, Thomas maintained a rotating trio dubbed the Accordion Club, which at various times included John Kirkpatrick, Chris Cutler, Garo Yellin, and Ira Kaplan.

Devoted to "spontaneous song generation", they feature Keith Moliné on guitar and Andy Diagram on "trumpet through electronics;" both make frequent use of MIDI, giving them a broader tonal palette than might be expected from two instruments.

He has staged his "improvisational opera" Mirror Man[12] at venues in Europe and North America, featuring at various times contributions from many of his previous collaborators, as well as Linda Thompson, Bob Holman, Robert Kidney, Van Dyke Parks, Frank Black, George Wendt, and Syd Straw.

Most recently he has alternated recording and performances primarily between Pere Ubu, David Thomas and Two Pale Boys, and the reunited Rocket from the Tombs.